Rocket and space engine systems can employ different engine configurations and engine types that reflect the particular mission, launch requirements, as well as the types of payloads expected. In liquid-fueled engine configurations, fuel and oxidizer types can be selected according to energy needs, specific impulse characteristics, and other factors. However, the design and components used for rocket engines can vary considerably based upon the fuel and oxidizer selections. These components can include propellant tanks, feed lines, pumps, propellant injection components, and combustion chambers, among other components. Propellant tanks can be employed for both fuel and oxidizer in various implementations.
When propellant tanks are employed, these tanks might employ gas pressurization of head space or ullage space that can remain in the propellant tanks after liquid propellant has been consumed. One example for pressurizing propellant tanks is based on having a large initial amount of ullage. In this example, propellant tanks are initially partially filled with propellant, with a remaining volume comprising a pre-pressurized inert pressurant gas. However, using an inert pressurant gas might require large and heavy propellant tanks since the tanks are designed for a greater initial pressure. Also, this example does not allow for control of the propellant tank pressure profile, and therefore thrust. Another approach for pressurizing propellant tanks in a pressure-fed propulsion system can involve using a separate supply of inert gas, which is pumped or pre-pressurized and fed to the propellant tanks to fill the propellant tanks volume that has been vacated by consumed propellants.
However, these inert gas systems can also be heavy, complex, expensive, and prone to component failures. An amount of required inert pressurant gas might be reduced by heating it, such as via a heat exchanger by the engine, or by employing trace propellant gasses mixed with an inert pressurant gas at levels which do not make the inert pressurant gas flammable. This mixture can be then run over a catalyst bed, triggering the combustion of the trace propellant gasses which heats up the inert pressurant gas. However, as with inert gas systems, these catalyst-based systems can be expensive, heavy, and can add complexity and risks of leakage, particularly over long missions.
Overview
Various enhanced rocket engine systems are discussed herein. In one implementation, a rocket engine system includes a combustion chamber, and at least one propellant tank that holds propellant in at least a liquid state. The rocket engine system also includes a pump configured to pump liquid propellant from the at least one propellant tank through a thermoelectric generator (TEG) system and a heat exchanger. The TEG system is configured to produce electrical power for the pump based at least on a temperature differential between the liquid propellant from the at least one propellant tank and heat produced in the combustion chamber during an active state of the rocket engine. The heat exchanger is configured to receive heat from the combustion chamber and pressurize the at least one propellant tank by heating at least partially liquid propellant received from the TEG system.
This Overview is provided to introduce a selection of concepts in a simplified form that are further described below in the Technical Disclosure. It should be understood that this Overview is not intended to identify key features or essential features of the claimed subject matter, nor should it be used to limit the scope of the claimed subject matter.